She scored three number one hits before her 18th birthday. Then she charmed the nation as Rose Tyler, Doctor Who's oh-so-amiable assistant. And now sheâs playing a high-class hooker in ITV2âs tsk-inducing sex-fest Secret Diary of a Call Girl. As we prepare to see more of Billie than ever before â you won't believe what she gets up to in tomorrow night's opening episode â it's time to swot up on the lovely Miss Piper. Read on for ten fascinating facts about the nation's favourite popstar-turned-actress.

1. Billie was originally called Leanne. Her parents changed her name - and duly altered her birth certificate - three weeks after registering her birth.

2. Billie's first TV job was an appearance on Saturday morning kids' show Scratchy & Co.

3. But her big break came when she scored a role in a Smash Hits TV ad. The fledgling actress blew a bubble in front of the camera, burst it with her finger and shrieked "Pop!" Nice work if you can get it, eh?

4. Billie also appears - uncredited - in the movie version of Evita.

5. Who is Billie's biggest celebrity crush? "Steve Coogan does something for me. He is so naughty, but I quite fancy him," she confides. "I've thought about having sex with him once or twice."

6. Billie made her stage debut in a touring production of Christopher Hampton's Treats earlier this year. However, she has no immediate plans to tread the boards again. "I think I need to stay away from the stage for a good couple of years," she admits. "The last time was just so scary, I can't tell you."

7. Billie has kept all her outfits from the Call Girl shoot. Lucky Laurence!

8. Would Billie ever revive her pop career? "Probably not," she says. "I always felt slightly fraudulent as a singer because I knew acting was what I really wanted to do."

9. Billie took lessons from a real-life dominatrix while researching her Call Girl role. Eek. We hate to think how she was punished when her concentration slipped.

10. Billie dubbed her Doctor Who colleague David 'Teninch', but what did he call her? "He knows me as Carlos Carlos," Billie reveals. "Just because we think Carlos is such a funny name, so I like to use it twice." Hmm. We imagine you probably had to be there.